1. Field of the Invention
This invention relates to apparatus and methods for applying interconnect bumps to an integrated circuit. More specifically, this invention relates to apparatus including a wedge bonder assembly with a new bonding tool and to methods employing such tool for applying interconnect bumps or pads to an integrated circuit or an integrated circuit die.
2. Description of Related Art
Semi-conductor or integrated circuit (IC) elements conventionally have raised input/output contact points, normally called interconnect bumps. Such bumps serve as terminals for attaching interconnect leads from the integrated circuits or integrated circuit dies to conductors on a substrate or circuit board. As used herein the term "integrated circuit" refers to both integrated circuits and integrated circuit dies.
Current methods of applying the bumps include relatively complicated electroplating methods for depositing the bump material, and conventional ball bonder methods for applying ball bumps. These methods often involve several steps. For example, such electroplating methods include photo etching of various materials to obtain a correct masking for the desired circuit design and one or more electroplating steps. These electroplating methods are relatively expensive to practice and can be accomplished only when adequate facilities and equipment are available. Ball bonder methods for applying bumps to integrated circuit chips include subjecting the initial ball bumps to planarization or tamping to provide the final ball bumps with flat top surfaces. This additional planarization or tamping operation limits speed, and increases cost. Further, the ball bumps may have varying diameters/sizes depending on the amount of material/wire remaining after being terminated and tamped into the bumps. Depending upon the application, variances in bump size may be unacceptable. In addition, the minimum size of the ball bumps is limited by the ball size. Thus, consistent ball bumps of less than about 3 mils (0.003 inches) in diameter are difficult to achieve.
Conventionally, wedge bonders are used to provide wire or ribbon connections between two points, for example, on the surface of an integrated circuit. Thus, the wedge bonder is used to make two discrete bonds with a wire or ribbon being attached or bonded to a first point and the wire ribbon being looped and then bonded to a spaced apart second point. Such wedge bonders have heretofore not been suggested for use in applying interconnect bumps to integrated circuits.
It would be advantageous to provide simplified and cost and time effective systems for applying interconnect bumps to integrated circuits.